Deep vein thrombosis is of extreme clinical importance as it carries the short-term risk of pulmonary embolism and death and the long term risk of chronic venous insufficiency, causing disabling symptoms of swelling, chronic pain, and skin ulceration (post thrombotic syndrome). Both pulmonary embolism and post-thrombotic syndrome may develop after symptomatic or asymptomatic, proximal or distal deep vein thrombosis events. Prevention of these short-term and long-term sequalae is of great clinical, economic, medical, and legal significance.
Due to the silent nature of deep vein thrombosis and pulmonary embolism, prevention has been the conventional clinical approach to avoid this disease. More specifically, prevention protocols have been conventionally used with any high-risk patients and especially with surgical patients. Conventional prevention therapies include either chemoprophylaxis (anticoagulant drugs) or mechanical (systems that enhance the venous return by compressing the legs).
Despite great progress with these two modalities of prevention in the recent years, conventional prevention therapies pose a high failure rate and a significant risk to surgical patients. Meta analysis studies showed that failure rate of the most common anticoagulant drug, LMWH, is about 16% in patients under going total hip replacement and 31% with patient undergoing total knee replacement. Given such a high failure rate there is a great need for routine screening to role out DVT in high risk patients. The conventional prevention therapies do not address the need to detect deep vein thrombosis in patients in which the prophylaxis has failed. More specifically, deep vein thrombosis screening is, conventionally, only done with patients who are suffering from clinical symptoms, and only 5% of the deep vein thrombosis patients have clinical manifestation.
Deep vein thrombosis can be conventionally diagnosed using venography, an invasive and relatively high-risk method, or a duplex scan. Both conventional diagnostic methods are expensive and can be done only in the hospital settings by a skilled technician. Thus, routine scanning for deep vein thrombosis with either duplex or venography is not cost effective; and therefore, scanning is not conventionally used.
Conventionally, once clinical symptoms are present (only about 5% of the deep vein thrombosis patients show clinical signs during the first 3-5 post operation days), a patient will go through a duplex scan to confirm or rule out the presence of deep vein thrombosis to allow for adequate treatment to be taken. There are two major down sides to this conventional approach.
The first problem is as the scan can only be made in the hospitals settings, the scans are done relatively a short time after the operation, usually just before discharge (3-5 days after the operation). However, many of the deep vein thrombosis situations are either too small to be detected at this time or even start manifestation later.
The second problem is that the current available scans are a one time “snap shot” of the patient's situation and cannot provide an understanding with respect to earlier or later situations. Therefore, a positive scan can often time detect a fully developed clot that could have been controlled if it was discovered earlier. Alternatively, a negative scan could miss a small clot that is about to develop, post discharge, into a significant clot.
With respect to the use of the anticoagulant drugs, anticoagulant drugs expose the patient to the serious risk of bleeding complications. For example, it is known that 2%-5% of the patients using the anticoagulant drug, LMWH, for deep vein thrombosis prevention in joint arthroplasties experience serious bleeding complications.
In view of this serious side effect, since only about 50% of the patients who are at risk for developing deep vein thrombosis actually develop deep vein thrombosis, more than half of the at-risk patients are subjected to a totally unnecessary risk of bleeding due to the conventional widespread use of anticoagulant drugs to prevent deep vein thrombosis.
Furthermore, as the conventional prophylaxis protocols are extended beyond the acute care time (10-30 days with joints arthroplasty patients), patients are being discharge with the risk of developing deep vein thrombosis due to prevention failure, of bleeding complications due to the continued use of anticoagulant drugs beyond the acute care time, or of both developing deep vein thrombosis and bleeding complications. It is noted that once the patient has detected a post acute care time problem and seeks clinical treatment, the situation is usually very serious or too late.
Therefore, it is desirable to provide a device that will detect, in real time and on a 24/7 basis, the possible formation of deep vein thrombosis in patients in acute care and/or post acute settings. Furthermore, it is desirable to provide a device that will be able to prevent deep vein thrombosis, in real time and on a 24/7 basis, as well as detect the possible formation of deep vein thrombosis. Moreover, it is desirable to provide a device that will provide deep vein thrombosis screening for patients receiving mechanical prophylaxis without any additional hardware.
Also, it is desirable to provide a device that will be able to reduce the rates of symptomatic deep vein thrombosis and pulmonary embolism by alerting the presence of an early formation of deep vein thrombosis and triggering early initiation of treatment. It is desirable to provide a device that can eliminate the risk of unnecessary bleeding associated with the wide use of anticoagulant by providing good prophylaxis capabilities together with good diagnostic capabilities in case of prophylaxis failure that together will eliminate the need to use anticoagulant drugs for the same purpose. It is further desirable to provide a device that will be able to protect against and detect deep vein thrombosis when the patient is out of the hospital.
In addition, it is desirable to provide a device that will be able to provide information on the progress of the condition and its acuteness or healing instead of providing a snapshot of the situation. Furthermore, it is desirable to provide a device that is capable of following dynamic trends that have been developed along treatment time axis and incorporate such dynamic trends into the decision-making algorithm.